Patent GB-191329883-A (GB)
Title: Improvements in Automatic Selecting Devices for Telephone Systems.
Filed: 1913-12-29
Granted: 1915-07-22
Abstract: 29,883. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. Dec. 29. Automatic and semi-automatic exchange systems.- Selectors are arranged to be available for extending a call in either direction, acting in the one case as call-finders and in the other case as group selectors or connectors. For example, the outgoing and incoming connexions of a group of 100 subscribers may be effected by fire call-finders, five connectors, and five switches capable of acting in either capacity, the double-acting switches being brought into use when all the call-finders or all the connectors are engaged. The invention is also applicable for enabling connexions to be made in either direction over junction lines. The test circuits may be such that when a calling line is tested by a connector before it is reached by a call-finder, the incoming call is refused, and if the connector is a doubleacting switch, it may be seized and used in its alternative capacity as a call-finder. On the other hand, the incoming call may be given the preference, even when the call-finder and connector arrive simultaneously on the calling line. Metering- circuits, private-branch exchange circuits, and arrangements for subscribers having more than one line are described. Specification 28,362/09 is referred to. Operation of double-acting switch DB, Fig. 1, as call-finder. The switch DB is a two co-ordinate selector, and its vertical movement to the level of terminals in which the calling line is connected, is controlled by a "tens" switch TS common to a group of lines. The switch TS is kept in connexion with an idle switch DB by a distributing- switch WS. The switch TS being in its normal position, the relay R of the calling line a, b energizes a high-resistance relay Q, which energizes the relays G, E of the pre-selected switch DB. The relay G locks itself in series with a relay U, marks the switch DB busy to the group selector IIGW, and completes an interrupter circuit through the vertical magnet H of the switch DB and the stepping-magnet TD of the tens switch TS. At the same time that the switch DB reaches the level of terminals in which the calling subscriber is connected, the switch TS arrives on the grounded contact corresponding to his tens digit, and the relay TP is energized and connects up the rotary magnet D in place of the magnets H, TD. When the switch DB reaches the calling line, the relay P1 is energized in series with the cut-off relay T, which cuts in the resistance w1 to mark the line non-selectable to other call-finders. The relay P1 de-energizes the relays G, E, U and energizes a relay An, which initiates the extension of the connexion through a second call-finder to a group selector and connector. The relay U de-energizes a holding-magnet TM, and the switch TS returns to normal. Operation of double-acting switch DB as connector. When the switch DB is seized by a group selector IIGW, relays X, Y are energized which (1) open the circuit of the relay P1, (2) prepare the circuit of a second test relay P2, (3) connect the vertical and rotary magnets H, D to the main leads from the group selector, and (4) mark the switch DB busy to the call-distributing switch WS. When the switch DB has been set on the wanted line, a resistance w3 is cut into the incoming test lead to de-energize the relay Y, which completes a test circuit through the relays P1, T, P2 over the third and fourth wipers c, d in series. If the line is already engaged, the relay T being in that case energized, there is battery potential on the terminal tested by the wiper c, and the circuit through the wiper d includes the resistance w1, so that neither of the relays P1, P2 is energized. If the wanted line has just originated a call, the relay R, but not the relay T, being in that case energized, the circuit through the wiper c is open at the contact 38, but the relays P1, T are energized in series over the wiper d, and the switch DB is taken into action as a call-finder, the connexion with the group selector IIGW being left open at the contacts 39, 40. If, however, the wanted line is idle, the relays P1, T, P2 are energized in series and remain locked in two parallel circuits closed by the contact 24. Metering and release. While the selector IIGW and connector LW, Fig. 2, are being set and during the conversation between the subscribers, the outgoing test circuit through the metering-relay ZR, Fig. 1, includes a resistance w4, w5, or w6 which prevents the energization of this relay. When the calling subscriber hangs up his receiver, the test circuit is directly earthed through a back contact r4 nf the relay R1 and a front contact v4 of the slowrelease relay V2, which was energized when the called subscriber answered the call. This energizes the relay ZR, which unlocks the relays T, P1, and the circuit of the meter Z is closed over the a speaking- lead by the contacts 75, Fig. 1, and v8, Fig. 2, the latter being closed by the relay V3 when the relay P1 de-energizes. A moment latter, the sluggish relay P1 de-energizes and opens the circuit of the relay C, which closes the circuit of the release magnet M. Alternative metering -arrangements. The meter Z, Fig. 5, is polarized, and the metering-relay ZR is arranged to cut a reverse battery B, into its circuit. The relay ZR may be energized by the shortcircuiting of a resistance w8 when the called subscriber replies, or it may be energized, as in the arrangement shown in Figs. 1 and 2, when the connexion is released. Alternative test circuits. In the arrangement shown in Fig. 4, an incoming call is given preference over a simultaneous .outgoing call by the shortcircuiting of the resistance w7 by the relay X. An arrangement in which both operations of a doubleacting switch are controlled over the circuit of a single test wiper is shown in Fig. 7. When the switch is in use as a call-finder, the test circuit includes a relay P which is adjusted to respond only when the resistance w in the circuit of the low-resistance winding 27 of the cut-off relay T is short circuited by the line relay R. When the switch is in use as a connector, a relay V1 is energized, which replaces the relay P by a second test relay P1, which is adjusted to become energized in series with the resistance w and low-resistance winding 27 of a disengaged line, but does not respond in series with the high-resistance winding 30 in the circuit of a busy line. The employment a single test circuit in this way is claimed in the divided Specification 21,793/14. Private-branch exchange systems &c. Doubleacting switches of the sort described may be installed at a private-branch exchange, as shown in Fig. 7. (1) Outgoing calls. The call-relay R energizes a "tens" relay TG, which energizes a starting relay E and ground a contact 8 in the path of an auxiliary wiper 9 of the switches DB. The relay E energizes a relay F of the switch DB preselected by the distributor WS, and the relay F completes an interrupter circuit through the vertical magnet H. When the switch DB reaches the level in which the calling subscriber is connected, a relay G, energized over the auxiliary wiper 9, opens the circuit of the vertical magnet H and closes that of the rotary magnet D. When the switch DB reaches the calling line, the relay P opens the circuit of the rotary magnet, and a line relay Y energizes a relay V, which bridges a relay R1 across the outgoing line. This energizes a relay AR which lights the call-lamp AL, and the operator attends to the call by inserting a plug VS in the jack AK. If the main exchange HA is an automatic one, the subscriber N sends impulses, which are repeated by the relay Y. In either case, the release magnet M is energized by the de-energization of the relay V when the calling subscriber hangs up his receiver. (2) Incoming calls. Upon the insertion of the plug VS in the jack AK, a relay J is energized which locks itself up and connects the relay R, to the line a', b<1>. The relay R, energizes a relay V1, so that the line-interruptions produced by the operator's number-switch Nu affect the vertical and rotary magnets H, D, the side switch s', s<11> being moved to its second and third positions at the termination of the two sets of impulses, by a magnet S controlled by the sluggish relay V2. If the wanted line is idle, the test relay P, is energized and closes the circuit of the ringing-relay L, which is cut out by the relay V when the subscriber replies. The release magnet M is energized when the called subscriber hangs up his receiver, or when the operator depresses a key 72. (3) A system is described in which outgoing calls are made, as in the arrangement shown in Fig. 7, without the assistance of an operator at the branch exchange, while incoming calls are made by the switch DB under control of a local operator. (4) Where the lines served by a double-acting switch DB at a main exchange include several which are alloted to the same subscriber, it is necessary, as regards this group of lines, that the switch DB should stop on a particular line in the case of outgoing calls, but should test all the lines, to find an idle one, in the case of incoming calls. This may be effected by employing a segment La, Fig. 9, which closes contacts 1, 2 when the wipers are on the terminals of any line of the group in question. When connexion is to be made to a line of the group I, II, III, a number of impulses are sent corresponding to the last line of the group. The contacts y3, y4 in the test circuit are not closed until all the impulses have been sent ; but when the wipers arrive on the terminals of any idle line of the group, the test circuit is completed through the relay P, contact 1, wiper d, relay T, wiper c, contact 2, and contact x5, and the relay P opens the circuit of the rotary magnet D. The relay T at the same time marks the selected line non-selectable to other switches by cutting in its high-resistance winding 2. Release of call finders when